1. Field of the Invention
This invention relates to optionally foamed intumescent masses based on polyurethanes containing, as a component of their formulation, a combination of specific polyethers and/or polyesters and phosphates of the melamine phosphate type and having a plastic-elastic character.
2. Description of the Prior Art
Intumescent masses are materials which foam up in the presence of fire and heat to form an insulating and fire repellent foam which protects the regions behind it from the effect of fire. Such intumescent masses are known in the form of lacquers, coatings, mortars and putties.
Good intumescent masses should be able to at least double their volume in contact with fire and should be water resistant. It is of particular technical interest to be able to obtain these properties in the absence of halogens and in combination with a low unit weight, i.e. a certain insulating effect in the unstressed state, as well as plasticity, flexibility and/or elasticity.
Elastic-plastic intumescent masses with good dimensional stability would have numerous applications in the field of preventive fire protection both when used in situ and in the form of semi-finished products such as bands, pates, wrappings, profiles, coatings, granulates or fillings such as puddling compositions.
The use of melamine in the manufacture of flexible foams from substantially linear polyols, in particular polyether polyols, is already known in principle (DE-OS 2,815,554). Although these foams are flame resistant and do not burn down completely when exposed to flames, they by no means have the character of intumescent masses and are not found to undergo an increase in volume to form a fire repellent foam when exposed to flames.
According to an earlier proposal (German patent application P 30 25 217.6), flame resistant sealing compounds free from phosphorus and halogen can be prepared using branched polyesters containing hydroxyl groups. These sealing compounds also do not have an intumescent character, that is to say they do not foam up on exposure to fire.
Optionally foamed intumescent masses have also been disclosed in DE-OS 3,041,731 and DE-OS 3,109,352.
Even though such optionally foamed intumescent masses have the desired characteristics to a sufficient degree, it still would be desirable to be able to replace these phosphorus-containing condensation products by more readily available or less water soluble phosphorus-containing compounds. It would be even more desirable to find a material capable of combining the role of a cyanuric acid derivative having the nature of a filler with that of a phosphorus-containing condensation product.
It has now surprisingly been found that it is possible to obtain optionally flexible intumescent masses which do not require the complicated structure of phosphorus-containing condensation products and wherein the cyanuric acid derivatives may be replaced. This means that a substantially simpler formulation may be used since the new intumescent masses can be obtained from a minimum of only three components instead of the four which were hitherto essential.
This is achieved by using readily available and less water soluble phosphates of the melamine phosphate type instead of the cyanuric acid derivative and the phosphorus-containing condensation product. It is now no longer necessary to use these two components which have been replaced although they may, of course, also be used since the additional use of these components may possibly provide advantages in the fire characteristics and capacity for intumescence.